Document which component properties can be tweaked from Script

While it's possible to set the 'Virtual' property from a component script, it's apparently not possible to set the 'Forced' property.

This should be fixed, or documented. If possible, we should also make the properties that can directly be manipulated via a property:

function Component() {
  if (systemInfo.productType() == "windows")
    component.forced = true;
}